@ -10,7 +10,7 @@
* Portions Copyright ( c ) 1994 , Regents of the University of California
*
* IDENTIFICATION
* $ Header : / cvsroot / pgsql / src / backend / port / sysv_shmem . c , v 1.10 2003 / 05 / 08 19 : 17 : 07 momjian Exp $
* $ Header : / cvsroot / pgsql / src / backend / port / sysv_shmem . c , v 1.11 2003 / 07 / 14 20 : 00 : 22 tgl Exp $
*
* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
*/
@ -45,10 +45,8 @@ void *UsedShmemSegAddr = NULL;
static void * InternalIpcMemoryCreate ( IpcMemoryKey memKey , uint32 size ) ;
static void IpcMemoryDetach ( int status , Datum shmaddr ) ;
static void IpcMemoryDelete ( int status , Datum shmId ) ;
static void * PrivateMemoryCreate ( uint32 size ) ;
static void PrivateMemoryDelete ( int status , Datum memaddr ) ;
static PGShmemHeader * PGSharedMemoryAttach ( IpcMemoryKey key ,
IpcMemoryId * shmid , void * addr ) ;
IpcMemoryId * shmid ) ;
/*
@ -243,41 +241,6 @@ PGSharedMemoryIsInUse(unsigned long id1, unsigned long id2)
}
/* ----------------------------------------------------------------
* private memory support
*
* Rather than allocating shmem segments with IPC_PRIVATE key , we
* just malloc ( ) the requested amount of space . This code emulates
* the needed shmem functions .
* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
*/
static void *
PrivateMemoryCreate ( uint32 size )
{
void * memAddress ;
memAddress = malloc ( size ) ;
if ( ! memAddress )
{
fprintf ( stderr , " PrivateMemoryCreate: malloc(%u) failed \n " , size ) ;
proc_exit ( 1 ) ;
}
MemSet ( memAddress , 0 , size ) ; /* keep Purify quiet */
/* Register on-exit routine to release storage */
on_shmem_exit ( PrivateMemoryDelete , PointerGetDatum ( memAddress ) ) ;
return memAddress ;
}
static void
PrivateMemoryDelete ( int status , Datum memaddr )
{
free ( DatumGetPointer ( memaddr ) ) ;
}
/*
* PGSharedMemoryCreate
*
@ -289,6 +252,9 @@ PrivateMemoryDelete(int status, Datum memaddr)
* collision with non - Postgres shmem segments . The idea here is to detect and
* re - use keys that may have been assigned by a crashed postmaster or backend .
*
* makePrivate means to always create a new segment , rather than attach to
* or recycle any existing segment .
*
* The port number is passed for possible use as a key ( for SysV , we use
* it to generate the starting shmem key ) . In a standalone backend ,
* zero will be passed .
@ -307,8 +273,7 @@ PGSharedMemoryCreate(uint32 size, bool makePrivate, int port)
/* Just attach and return the pointer */
if ( ExecBackend & & UsedShmemSegAddr ! = NULL & & ! makePrivate )
{
if ( ( hdr = ( PGShmemHeader * ) memAddress = PGSharedMemoryAttach (
UsedShmemSegID , & shmid , UsedShmemSegAddr ) ) = = NULL )
if ( ( hdr = PGSharedMemoryAttach ( UsedShmemSegID , & shmid ) ) = = NULL )
{
fprintf ( stderr , " Unable to attach to proper memory at fixed address: shmget(key=%d, addr=%p) failed: %s \n " ,
( int ) UsedShmemSegID , UsedShmemSegAddr , strerror ( errno ) ) ;
@ -317,34 +282,29 @@ PGSharedMemoryCreate(uint32 size, bool makePrivate, int port)
return hdr ;
}
/* Create shared memory */
NextShmemSegID = port * 1000 + 1 ;
/* Loop till we find a free IPC key */
NextShmemSegID = port * 1000 ;
for ( ; ; NextShmemSegID + + )
for ( NextShmemSegID + + ; ; NextShmemSegID + + )
{
/* Special case if creating a private segment --- just malloc() it */
if ( makePrivate )
{
memAddress = PrivateMemoryCreate ( size ) ;
break ;
}
/* Try to create new segment */
memAddress = InternalIpcMemoryCreate ( NextShmemSegID , size ) ;
if ( memAddress )
break ; /* successful create and attach */
/* Check shared memory and possibly remove and recreate */
if ( ( hdr = ( PGShmemHeader * ) memAddress = PGSharedMemoryAttach (
NextShmemSegID , & shmid , UsedShmemSegAddr ) ) = = NULL )
if ( makePrivate ) /* a standalone backend shouldn't do this */
continue ;
if ( ( memAddress = PGSharedMemoryAttach ( NextShmemSegID , & shmid ) ) = = NULL )
continue ; /* can't attach, not one of mine */
/*
* If I am not the creator and it belongs to an extant process ,
* continue .
*/
hdr = ( PGShmemHeader * ) memAddress ;
if ( hdr - > creatorPID ! = getpid ( ) )
{
if ( kill ( hdr - > creatorPID , 0 ) = = 0 | | errno ! = ESRCH )
@ -407,22 +367,25 @@ PGSharedMemoryCreate(uint32 size, bool makePrivate, int port)
/*
* Attach to shared memory and make sure it has a Postgres header
* Attach to shared memory and make sure it has a Postgres header
*
* Returns attach address if OK , else NULL
*/
static PGShmemHeader *
PGSharedMemoryAttach ( IpcMemoryKey key , IpcMemoryId * shmid , void * addr )
PGSharedMemoryAttach ( IpcMemoryKey key , IpcMemoryId * shmid )
{
PGShmemHeader * hdr ;
if ( ( * shmid = shmget ( key , sizeof ( PGShmemHeader ) , 0 ) ) < 0 )
return NULL ;
hdr = ( PGShmemHeader * ) shmat ( * shmid , UsedShmemSegAddr ,
hdr = ( PGShmemHeader * ) shmat ( * shmid ,
UsedShmemSegAddr ,
# if defined(solaris) && defined(__sparc__)
/* use intimate shared memory on SPARC Solaris */
SHM_SHARE_MMU
/* use intimate shared memory on Solaris */
SHM_SHARE_MMU
# else
0
0
# endif
) ;
@ -434,5 +397,6 @@ PGSharedMemoryAttach(IpcMemoryKey key, IpcMemoryId *shmid, void *addr)
shmdt ( hdr ) ;
return NULL ; /* segment belongs to a non-Postgres app */
}
return hdr ;
}
Tom Lane
22 years ago